Intel 80C188XL User Manual

Page 345

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INSTRUCTION SET DESCRIPTIONS

C-22

JCXZ

Jump if CX Zero:

JCXZ

disp8

Transfers control to the target location
if CX is 0. Useful at the beginning of a
loop to bypass the loop if CX has a
zero value, i.e., to execute the loop
zero times.

Instruction Operands:

JCXZ short-label

if

(CX) = 0

then

(IP)

(IP) + disp8 (sign-ext to 16 bits)

AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –

JE
JZ

Jump on Equal:
Jump on Zero:

JE disp8
JZ

disp8

Transfers control to the target location
if the condition tested (ZF = 1) is true.

Instruction Operands:

JE short-label
JZ short-label

if

(ZF) = 1

then

(IP)

(IP) + disp8 (sign-ext to 16 bits)

AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –

JG
JNLE

Jump on Greater Than:
Jump on Not Less Than or Equal:

JG disp8
JNLE

disp8

Transfers control to the target location
if the condition tested (SF = OF) and
(ZF=0) is true.

Instruction Operands:

JG short-label
JNLE short-label

if

((SF) = (OF)) and ((ZF) = 0)

then

(IP)

(IP) + disp8 (sign-ext to 16 bits)

AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –

JGE
JNL

Jump on Greater Than or Equal:
Jump on Not Less Than:

JGE

disp8

JNL

disp8

Transfers control to the target location
if the condition tested (SF=OF) is true.

Instruction Operands:

JGE short-label
JNL short-label

if

(SF) = (OF)

then

(IP)

(IP) + disp8 (sign-ext to 16 bits)

AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –

Table C-4. Instruction Set (Continued)

Name

Description

Operation

Flags

Affected

NOTE:

The three symbols used in the Flags Affected column are defined as follows:
– the contents of the flag remain unchanged after the instruction is executed
? the contents of the flag is undefined after the instruction is executed

ü

the flag is updated after the instruction is executed

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